It is well known in the art to provide a window having more than one pane of glass, the panes being separated by an airspace. Typically, such insulating windows have their glass panes separated by a frame interposed between the panes at their edges. The interior space between the panes then serves as an insulator to reduce heat flow through the glass. In the prior art it is known to manufacture the spacer frame of individual tubes made of aluminum joined at their ends to form a continuous frame. A sealant is injected around the perimeter of the glass panes to seal the glass panes and spacer frame into a single unit.
One disadvantage to the use of aluminum in the spacer frame separating the glass window panes is that the aluminum typically has a higher heat conductivity rating than the glass that it separates. Therefore, while the central portion of the window is an effective insulator by virtue of its glass-and-air construction, the edges of the window conduct heat at a more rapid rate because of the higher conductivity factor of the aluminum. Also, in situations where there are extremes of temperature encountered by the window, the coefficient of expansion of the aluminum and the glass will be different and internal stresses will build up along the edges of the glass panes due to the unequal rates of expansion of the glass and aluminum members. It would be advantageous to have a glass panel comprised of separated glass panes in which the separation was accomplished by a medium having a similar heat conductivity rating to the glass panes and a coefficient of thermal expansion equivalent to that of the glass panes.